The present invention relates to a switching device in which a rod is pivotally attached into a rod case.
The configuration of a related-art switching device will be described with reference to FIGS. 4 and 5. As shown in FIG. 5, a rod case 1 has the shape of a cylinder having openings at respective ends thereof. As shown in FIG. 4, a rod 3 is rotatably inserted into a cylindrical portion 2 of the rod case 1. A knob 4 is rotatably fitted to the right end of the rod case 1 and connected to the rod 3 through a pin 5.
Two sets, each set comprising a compression spring 6 and a moderation member 7, are attached to the knob 4 (only one set is illustrated). The moderation members 7 are pressed against a detent plate 8 under the force of the springs 6. The detent plate 8 is fastened to the rod case 1, and the knob 4 is selectively held in one of a plurality of control positions as a result of selective engagement of the moderation members 7 with a plurality of indentations 9 (see FIG. 5) of the detent plate 8 under the force of the springs 6.
A control portion 10 is formed at the left end of the rod 3, and a contact holder 11 is engaged with the control portion 10. A movable contact 12 is held by the contact holder 11. When the knob 4 is turned, the control portion 10 is rotated integrally with the rod 3, thereby sliding a movable contact 12. The movable contact 12 is selectively brought into electrical connection with any one of stationary contacts.
As shown in FIG. 5, the rod 3 is inserted in to the cylindrical portion 3 of the rod case 1 from the left side. Hence, the size of the rod 3 is limited by the internal diameter of the cylindrical portion 3. When an attempt is made to employ only one set consisting of the spring 6 and the moderation member 7, the portion of the rod 3 close to the moderation member 7 becomes deflected under the force of the spring 6, as designated by a two-dot chain line shown in FIG. 4. As a result, the knob 4 is inclined toward the rod case 1, so that the clearance between the rod case 1 and the knob 4 becomes greater in portion A and smaller in portion B. Hence, use of one set consisting of the spring 6 and the moderation member 7 is not sufficient.
The present invention has been conceived in light of the foregoing circumstances and aims at providing a switching device capable of holding constant a clearance between a rod case and a knob by means of one set consisting of a spring and a moderation member.
In order to solve the aforesaid object, the invention is characterized by having the following arrangement.
(1) A switching device comprising:
a cylindrical rod case opened at opposite ends thereof;
a rod rotatably provided in the rod case, the rod including,
a first rod including a control portion for actuating a movable contact, and
a second rod including a knob for actuating the rod and having a diameter larger than a diameter of the first rod, wherein the first and second rods are engaged with each other within the rod case;
a moderation surface including a plurality of indentations and provided in the rod case; and
a moderation member and a spring which are provided in the second rod, wherein the moderation member is selectively engaged with any one of the plurality of indentations on the moderation surface under force of a spring according to a pivotal movement of the knob.
(2) The switching device according to (1), wherein
the second rod is provided with a large-diameter portion to which the knob is fitted in an axial direction of the second rod,
the first and second rods are provided with rod engagement portions which are engaged each other when the first and second rods are inserted into the rod case from opposite ends thereof, respectively, and
the knob and the large-diameter portion are provided with knob engagement portions which are engaged each other when the knob is fitted to the large-diameter portion in the axial direction.
(3) The switching device according to (2), wherein
the control portion and the rod engagement portion are formed at opposite ends of the first rod, respectively, and
the large-diameter portion and the rod engagement portion are formed at opposite ends of the second rod, respectively, and
the control portion and the large-diameter portion are exposed to the exterior of the rod case when the rod engagement portions are engaged each other.
(4) The switching device according to (2), wherein
one of the rod engagement portions includes a rail groove extending in the axial direction,
the other of the rod engagement portions includes a rail extending in the axial direction, and
when the rod engagement portions are engaged each other, the rail groove is engaged with the rail so as to prevent positional displacement in a circumferential direction of the rod between the first and second rods.
(5) The switching device according to (2), wherein
one of the knob engagement portions includes a rail groove extending in the axial direction,
the other of the rod engagement portions includes a rail extending in the axial direction, and
when the knob engagement portions are engaged each other, the rail groove is engaged with the rail so as to prevent position displacement in a circumferential direction of the rod between the second rod and the knob.